Study: Marijuana use and short-term outcomes in patients hospitalized for acute myocardial infarction

Author Introduction: Medicinal and recreational marijuana use is increasing worldwide, partially due to legislative changes in the United States, Europe and South America. The World Health Organization estimates that approximately 2.5% of the world’s population use cannabis, ten times more than cocaine (0.2%) or opiates (0.2%). Furthermore, cannabis use is increasing more rapidly than use of either cocaine or opiates. In the United States, nearly 55 million adults use marijuana at least yearly. Of those 55 million adults, 35 million consume marijuana monthly and it is estimated that there are 8.5 million daily marijuana users. Thirty states and the District of Columbia currently have laws broadly legalizing marijuana (medicinal or recreational) with an additional 12 states considering marijuana legislation in 2018. With the rapidly changing legal landscape surrounding marijuana, the number of people using marijuana is likely to increase.

There are known benefits of marijuana for treating numerous medical conditions such as cancer, glaucoma, HIV/AIDS and posttraumatic stress disorder. However, with the increase in use, there is an alarming increase in reports of adverse cardiovascular events following marijuana exposure. Meta-analysis of over 3,500 participants (38% who reported marijuana use) in the CARDIA study showed a positive correlation between marijuana use, hypertension and dyslipidemia, all of which may contribute to coronary artery disease. In addition, a French study recently analyzed 35 reports of “remarkable” cardiovascular complications following marijuana use. During the 5-year study period (2006–2010) 1979 adverse events were reported, 35 (1.8%) of which were cardiovascular related. The cardiovascular events were categorized into cardiac or extra-cardiac (i.e. vascular) events: acute coronary syndrome (ACS) composed 57% of the reports; heart rate disorders 5.7%; cerebral vascular events 8.6%; and peripheral vascular events 28.7%. Unfortunately, over 25% of these cases resulted in death even though the overall mean age of the patients was only 34.5 years. It is important to note, however, that there were an estimated 1.2 million regular marijuana users in France at the time of the study and that the nearly 2000 reported adverse events represents an extremely low complication rate, perhaps due to under-reporting of marijuana use.

These studies strongly suggest an effect of cannabis on cardiovascular health. Importantly, federal data from 2014 revealed that for the first time, middle-aged Americans were slightly more likely to use marijuana than their teenage children; data from the Centers for Disease Control and Prevention reported a 10% decline in regular marijuana use by teenagers (12–17 years) from 2002 to 2014, whereas use increased by 8% in those aged 35–44, by a surprising 50% in Americans aged 45–54, and by a stunning 455% among those aged 55 to 64 years old during the same time period. Age is a well-known risk factor for cardiovascular diseaseand with rising marijuana consumption in older individuals, it is increasingly likely that patients with common cardiovascular conditions such as AMI will be regular marijuana users.

Few studies, however, have examined the impact of marijuana use on outcomes following cardiovascular incidents such as AMI, and they are limited by small sample sizes. One study aimed at quantifying long-term outcomes in marijuana users post-AMI found no association between marijuana consumption and long-term mortality in 2097 post-AMI patients (109 marijuana users) followed up to 18 years. Recently, Desai, et al analyzed large, weighted dataset with nearly 500,000 index admissions and reported that lifetime odds of acute myocardial infarction were increased 3–8% in marijuana users. Desai et al found no increase in in-hospital mortality in the marijuana users following AMI and the authors were able to identify a number of independent predictors of inpatient mortality in the marijuana using group. These findings underscore the need to further assess the effect of marijuana use on the cardiovascular system. Accordingly, the aim of this retrospective study was to quantify short-term outcomes in marijuana-using and non-using patients hospitalized with AMI. Based on the limited published data, we hypothesized that marijuana use would be associated with worse in-hospital outcomes in AMI patients.

The Study

Marijuana use and short-term outcomes in patients hospitalized for acute myocardial infarction

Abstract: Marijuana use is increasing worldwide, and it is ever more likely that patients presenting with acute myocardial infarctions (AMI) will be marijuana users. However, little is known about the impact of marijuana use on short-term outcomes following AMI. Accordingly, we compared in-hospital outcomes of AMI patients with reported marijuana use to those with no reported marijuana use. We hypothesized that marijuana use would be associated with increased risk of adverse outcomes in AMI patients. Hospital records from 8 states between 1994–2013 were screened for patients with a diagnosis of AMI. Clinical profiles and outcomes in patients with reported use of marijuana were compared to patients without reported marijuana use. Short-term outcomes were defined as adverse events that occurred during hospitalization for an admitting diagnosis of AMI. The composite primary outcome included death, intraaortic balloon pump placement, (IABP), mechanical ventilation, cardiac arrest, and shock. In total, 3,854 of 1,273,897 AMI patients reported use of marijuana. The marijuana cohort was younger than (47.2 vs. 57.2, respectively) and had less coronary artery disease than the non-marijuana cohort. In multivariable analysis including age, race and common cardiac risk factors, there was no association between marijuana use and the primary outcome (p = 0.53), but marijuana users were more likely to be placed on mechanical ventilation (OR (odds ratio) 1.19, p = 0.004). Interestingly, marijuana-using patients were significantly less likely to die (OR 0.79, p = 0.016), experience shock (OR 0.74, p = 0.001), or require an IABP (OR 0.80, p = 0.03) post AMI than patients with no reported marijuana use. These results suggest that, contrary to our hypothesis, marijuana use was not associated with increased risk of adverse short-term outcomes following AMI. Furthermore, marijuana use was associated with decreased in-hospital mortality post-AMI.